The physical properties of a cell's environment are important factors in determining cell behavior and ultimately, phenotype. Among these factors, matrix rigidity can affect cell growth, differentiation and adhesion and motility. Alteration of the cellular rigidity sensing mechanism can be implicated in malignant transformation and tumerogenesis. Many aspects of the cellular rigidity-sensing mechanism are of interest, particularly in reference to tactile cell sensing of discrete localized areas of increased or decreased rigidity.
As well as responding to biochemical signals, cells can directly probe the physical properties of the extracellular environment around them, such as to determine force, shape, geometry and stiffness of the extracellular environment. The cells can probe the extracellular environment by adhering and initiating matrix deformation by the application of cellular tractive forces. Matrix or tissue elasticity can have a role in regulating multiple cell processes, including cell adhesion, cell migration, and differential function, through cell-generated actomyosin interactive forces regulated by a dynamic feedback mechanism.
The sensitivity of cells to the mechanical properties of the extracellular matrix can be attributable to the mechanosensitive nature of the molecules involved in the structures of cell adhesion. Among adhesive structures, focal adhesions appear to be the most prominent, demonstrating correlation between focal adhesion reinforcement and sustained force exhibiting a constant stress. This mechanosensitivity may be regulated by a conserved local mechanism in which subcellular forces induce an elastic deformation of transmembrane integrin regions, triggering conformational and organizational changes and resulting in integrin activation, which in turn can uncover cryptic binding sites for additional protein binding, enabling focal adhesion reinforcement. These processes can set a dimensional scale for cellular rigidity sensing.